1. FIELD OF THE INVENTION
This invention relates to mechanical shaft seals and more specifically to a shaft seal which is neither a purely component seal nor a purely cartridge-type seal. Rather, the semi-cartridge seal of the instant invention utilizes two cartridge components comprising inner and outer components each consisting of a plurality of assembled parts.
2. DESCRIPTION OF RELATED ART
Various forms of sealing devices have been used between stationary housing members and rotating shafts. These devices range from various braided and compressed packings to various types of end face mechanical seals. These end face mechanical seals vary in design from component seals which are assembled insitu on the shaft during equipment assembly to those designs which are termed cartridge seals such as that disclosed in U.S. Pat. No. 4,538,820 which are preassembled in a factory or other location and merely placed into position and fastened to the equipment by bolting, set screws or other similar methods.
Upon removal of some types of centering and spacing devices, the cartridge seal is ready for operation. The advantage of this preassembled cartridge-type seal has been ease of installation and longer seal life, partly due to the prevention of installation errors common to the aforementioned component design of seals which are assembled on the shaft. The errors primarily deal with errors in centering the stationary portion or portions of the seal around the rotating shaft or in precisely locating the rotating portion or portions of the seal in relation to the stationary portion or portions.